Improvement in screw-threaded pipe joints and couplings



W. O. ALLISON. Screw-Threaded Pipe Joint and Coupling.

No. 214,076. Patented April 8,1879.

ll: Al ie-Si 1 r IIIVBIlT OZ" i H} i5 ZZGCMM W I QWCWW UN TED STATESPATENT OFFICE.

WILLIAM G. ALLISON, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO W. O.ALLISON & 00., OF SAME PLACE.

IMPROVEMENT IN SCREW-THREADED PIPE JOINTS AND COUPLINGS.

Specification forming part of Letters Patent No. 2l4.0 76, dated April8, 1879; application filed February 8, 1879.

To all whom it may concern:

Be it known that I, WILLIAM C. ALLISON,

, finished section of screwthreaded pipe constructed according to myinvention; Fig. 2, a similar view of the same prior to the burnishing ofthe thread, and Fig. 3 an elevation of a coupling constructed accordingto my invention.

Similar letters of reference indicate corresponding parts wherever used.

This invention relates to galvanized or metalizioated screw-threadedpipe joints and coupngs.

As heretofore manufactured, galvanized pipe and such articles of kindredcharacter as embody in their construction screw-threads have in theirmakingbeen first galvanized and subsequently cut with threads, theeffect of which has been that the threaded portions have been divestedof the galvanic coating, with the result that when a portion of thethread is exposed, as in Fig. 3, it is subject to all the evil resultscommon to ungalvanized screwthreads.

The object of my invention is the making of galvanized, coppered, orother metal-coated screw-threaded pipe joints and couplings evenlycoated in all portions, to which end it consists, substantially, asfollows: The pipe joint or coupling which is to be galvanized ormetal-coated is first threaded in the usual manner, the thread cuttingbeing completed before the galvanizing or metal-coating process iscommenced. The threaded pipe or socket is then subjected to thegalvanizing or metal-coating operation until completely coated, afterwhich the thread-cut portions are burnished down even by any suitabledevice as, for instance, by a burnisher of analogous construction andoperation to the thread-cutting mechanism.

It will be understood that in the use of copper and some other metals itmay not be necessary to burnish or recut the metal-coated thread, saidthread being of suflicient ev'eir ness and smoothness to dispense withsuch burnishin g or recuttin g process.

Such being my invention, it is obvious that this invention provides ajoint of greater ti ghtness than it has been practicable heretofore toproduce, for the reason that an intermediate layer of soft metal isplaced between the screwthreaded contact surfaces of the pipe joint orcoupling, which forms a cushion or packing, with the result stated, andalso that, all portions being alike galvanized, the pipe is not at anypoint exposed to corrosive or other such destructive influence, as hasheretofore been the case.

Having thus described my invention, I claim and desire to secure byLetters Patentof the United States- 1. As a new article of manufacture,a screwthreaded pipe joint or coupling, the threaded surfaces of whichare provided with a zinc or other metal coating to form a packingbetween the contact surfaces of said joint.

2. The herein-described process of making galvanized or metal -coatedscrew threaded pipe joints or couplings, which consists in cutting thescrew-thread upon such pipe or coupling, then galvanizing ormetal-coating the cut screw, and finally burnishing or recutting themetal-coated threads, snbstantiall y I as shown and described.

In testimony whereof Ihave hereunto signed In presence of- J. BONSALLTAYLOR, J onn J OLLEY, Jr.

